共查询到20条相似文献,搜索用时 62 毫秒
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针对导弹雷达导引头测试数据获取困难、失效机理多样的问题,在分析导弹雷达导引头退化数据和失效数据特点的基础上,提出了一种退化失效与突发失效相关的竞争失效状态预测模型。针对退化数据的小样本、非线性和不确定性的特点,采用相关向量机(RVM)对其分布参数序列进行回归预测,并基于量子粒子化算法(QPSO)和Hannan-Quinn(H-Q)准则分别对核参数和嵌入维数进行寻优;考虑到突发失效与退化失效之间的相关性,引入位置-尺度模型描述突发失效分布参数与退化数据间的相关关系,进而对下一阶段导弹雷达导引头的失效状态进行预测。实例预测结果验证了模型的可行性及合理性。 相似文献
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精确制导空空导弹是一个复杂系统,及时、准确的识别和诊断导弹故障是化解风险的重要措施。由于导弹故障模式复杂,对其故障进行识别和诊断的难度很大。文中以某型空空导弹测试问题为例,提出一种基于BP神经网络算法的导弹故障自动识别与诊断技术。通过对导弹测试数据的采集和整理形成数据样本,利用神经网络系统的学习和判断能力自动识别及诊断导弹故障,并使用Matlab神经网络工具箱进行仿真验证。验证结果证明,该技术能够快速、准确的识别和诊断导弹故障。 相似文献
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针对电子设备的测试和故障识别提出了一种基于性能退化数据的缓变故障检测方法。首先,结合电子设备退化特点,选取合适的退化模型近似设备参数退化轨道,利用交叉熵得出退化数据与初始数据随时间变化的分布曲线;然后,通过与超限概率建立关系,确定故障判定的阈值;最后,以+12V稳压电源为检测对象,产生时变随机样本进行仿真验证。通过仿真分析:交叉熵方法可以比较准确的检测设备的缓变故障及老化,并且相对于检测超限概率提高了检测精度,减少了运算量;同时,交叉熵直接采用样本点进行故障检测,避免了需要拟合分布曲线计算超限概率的误差;最后,分析了样本数对交叉熵的影响,说明了为了兼顾稳定性和精确度,并不是样本数越多越好。 相似文献
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文中提出一种基于谱峭度等指标和支持向量机的滚动轴承性能退化评估的新方法。针对滚动轴承全寿命过程中各个时期故障损伤程度的不同,将故障监测分为4个阶段:正常、初期、中期、末期。通过与传统指标,例如均方根值、峭度值、峰峰值指标等对比,验证了谱峭度作为初期故障特征指标的优势。选取谱峭度等指标作为特征输入,构建多分类支持向量机预测模型来预测轴承性能退化阶段。使用轴承全寿命试验数据对预测模型进行检验,证明了该方法的有效性和可行性。 相似文献
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针对装备故障预测模型难以精确建立的特点,为提高故障间隔时间预测的准确度,提出了一种基于灰色组合模型的预测方法。该方法首先简化装备故障的阶段与属性,形成合理的建模背景;然后在引入灰色预测模型的基础上,按阶段建立了灰色线性回归模型和灰色马尔可夫组合模型,对装备故障间隔时间进行预测;最后计算预测值与真实值的误差,根据预测值基本确定下次故障发生的时间。经实例计算表明,在样本数据有限的情况下,根据不同故障阶段的特点,选用与被预测数据属性相应的灰色预测组合模型,可以有效降低预测误差,提高预测精度,预测结果可以作为装备保障人员早期拟订维修决策之用。 相似文献
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为了解决导弹武器故障数据量小,无法利用现有的方法对其进行故障预报的问题,在分析灰色预测模型与BP网络算法的基础上,对现有的一阶灰色神经网络模型做了进一步优化和完善,并在此基础上建立了基于时间响应函数的三阶灰色神经网络GNNM(3,1)模型,推导出了模型的理论算法。将此算法应用于导弹惯性器件故障预报中,通过实例证明了GNNM(3,1)模型对导弹武器故障预报的有效性。 相似文献
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Michael Reilly 《半导体技术》2004,29(12)
DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system. 相似文献
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High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET > PDMAT > TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center. 相似文献
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In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal (200) (2d = 0.4027 nm) is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line(w), the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line(x), the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines(y), the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line(z) in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line(q) in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution(λ/△ 2) is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy. 相似文献
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Thomas M.Trexler 《半导体技术》2004,29(5)
From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test. 相似文献
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The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high. 相似文献
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The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation. 相似文献
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Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible. 相似文献
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Qi-jiang Ran Pei-de Han Yu-jun Quan Li-peng Gao Fan-ping Zeng Chun-hua Zhao 《光电子快报》2008,4(4):239-242
This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel's. 相似文献
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This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors. 相似文献
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YUXiao-hua XIANGYu-qun 《半导体技术》2005,30(2):30-32,37
An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB. 相似文献